BIOL 115 Lecture Notes - Lecture 7: Cell Membrane, Endomembrane System, Passive Transport
Document Summary
Diffusion the random movement of molecules from a higher concentration to lower concentration. Molecules move in both directions, but net movement, is from high to low concentration. At equilibrium, the same number of molecules move in and out of the cell. Osmosis the diffusion of water molecule from high to low water concentration. Normally body fluids are isotonic to cells. The transport of molecules across the plasm membrane from higher concentration. Protein transporters are very specific and only move certain molecules. Requires a protein carrier, which is often called a pump. Active transport the movement of molecules from a lower to higher concentration to lower concentration via a protein carrier. Cells use bulk transport to move large molecules across the membrane. Endocytosis transports molecules or cells into the cell via invagination of the plasma membrane to form a vesicle. Phagocytosis endocytosis of pathogens (that is, bacteria) by white blood cells. Receptor-medicated endocytosis particles first bind to receptors in the plasma.
